Method of making expanded metal products

ABSTRACT

A post comprising a series of struts radiating outwardly from a central portion produced by a method of firstly extruding ductile metal to a constant cross-sectional shape which includes a central portion and at least three circumferentially spaced webs, punching a plurality of rows of slots in each web, arranging the lengths of the slots to be great compared with the distance between them and arranging the slots to be staggered, then stretching the metal between the slots of the rows so as to form a series of struts, the unpierced metal of the product constituting the chords of the trusses so formed.

[ June 26, 1973 METHOD OF MAKING-EXPANDED METAL PRODUCTS [75] Inventor:Trevor B. Ryan, Rose Park,

Australia [73] Assignee: Jury & Spiers Proprietary Limited,

Norwood, Australia 22 Filed: Aug. 18,1971

21 Appl.No.: 172,763

[30] Foreign Application Priority Data Aug. 24, 1970 Australia PA2297/7O[52] US. Cl 29/155 C, 29/6.l, 52/635 [51] Int. Cl 1323p 17/00 [58] Fieldof Search 52/634-637, 730, 732,692, 696, 670, 672; 29/6. 1 I55 [56]References Cited UNITED STATES PATENTS 1,927,442 9/1933 Laufle 52/6353,034,197 5/1962 Watawabe 521635 X FOREIGN PATENTS OR APPLICATIONS16,187 898 Great Britain 52/670 508,719 920 France r 52/635 485,923 970Switzerland 52/730 Primary Examiner-Thomas H. Eager Attorney-Oldham &Oldham [57] ABSTRACT A post comprising a series of struts radiatingoutwardly from a central portion produced by a method of firstlyextruding ductile metal to a constant cross-sectional shape whichincludes a central portion and at least three circumferentially spacedwebs, punching a plurality of rows of slots in each web, arranging thelengths of the slots to be great compared with the distance between themand arranging the slots to be staggered, then stretching the metalbetween the slots of the rows so as to form a series of struts, theunpierced metal of the product constituting the chords of the trusses soformed.

6 Claims, 8 Drawing Figures IPAIENIEDJUNZBIBH SHEEP 1 0F 7 (QM M 9 @MPAIENTED M25 3. 740. 812

SHEET'S 0F 3 METHOD OF MAKING EXPANDED METAL PRODUCTS This inventionrelates to a method of forming a metal product initially to a contracteddimension and subsequently expanded so as to include a plurality ofstruts, thereby interconnecting chords to form a truss.

Heretofore, trusses have been formed by the process of welding strutsbetween chords, but this process is slow and expensive. Furthermore theappearance of the trusses formed by this process is not aestheticallypleasing. Consequently, in such applications as street lamp posts,telegraph posts and the like, trusses are not favoured and in manyinstances composite steel and concrete members, or tubular members areused. In both cases, however, the cost is considerably higher than asimple truss, even if that truss is'of welded construction. One of theobjects of this invention is to provide an expanded metal product whichcan be utilised as a post, and wherein the cost will be less than, say,a tubular post of the same strength, or a similar welded truss, andwhich will at the same time be more pleasing aesthetically.

A product formed by the method of this invention consists of an expandedmetal product having a central portion, at least three circumferentiallyspaced trusses radiating outwardly from the central portion, saidcentral portion forming one chord of each respective truss, an outerportion on each respective truss forming another chord thereof, andstruts interconnecting the chords of the trusses and being inclinedthereto, the trusses comprising a single integral member of ductilemetal, and the metal contained within the struts being in a condition ofhaving been strained beyond its yield point by stretching.

According to the invention, the method an expanded metal productcomprises:

a. extruding ductile metal to form an extruded prodof forming uct havinga constant cross-sectional shape which includes a central portion withat least three circumferentially spaced webs radiating outwardlytherefrom, each web terminating at its outer end in an outer portion,and each web having a rib extending along it, each rib being between theouter portion and the central portion,

b. removing metal from each web so as to form a row of slots on eachside of the rib thereof, the length of each slot exceeding twice thelength of metal remaining between either one of its ends and theadjacent end of the next slot in the same row, and the slots of a row onone side of the rib being staggered relative to those of the row on theother side so as to form therib into a plurality of strut-formingportions, and

c. forcing respective said outer portions away from the central portionto thereby incline the strut-forming portions of the ribs relative bothto the respectiveouter portions and to the central portion and at thesame time elongate the metal thereof by stretching it, thus form-- ingstruts joining respective outer portions and the central portion so asto in turn form trusses, the chords of which are constituted by saidcentral portion and re-v spective said outer portions.

With this arrangement it becomes possible to construct a post which isvery pleasing in appearance and which has inbuilt conduit means. If aplurality of tubular members are utilised (either in the centralor outerportions), the post can be, for example, divided into 2. two, three ormore branches at its top end, and utilised for supporting street lamps,wiring or the like.

Embodiments of the invention are described hereunder in some detail withreference to and are illustrated in the accompanying drawings, in which:

FIG. 1 is an elevational view of a post,

FIG. 2 is a section through an extruded metal product which has aconstant cross-sectional shape, illustrating the first stage ofproducing the post,

FIG.- 3 is a fragmentary elevation showing the product of FIG. 2 butwith metal removed from the web,

FIG. 4 is-a diagrammatic section showing stretching of the strut-formingportions of the ribs of the product illustratedin FIG. 3,

FIG. 5 is a fragmentary elevation similar to that of FIG. 2 but showing(to a large scale) the configuration of the struts after stretching,

FIG. 6 is a diagrammatic plan view illustrating the means for andmethodof forcing outer portions away from the central portion to stretch thestrut-forming portions of the ribs and thus form them into struts,

FIG. 7 is an elevation of a post according to a second embodiment, and

FIG. 8 is a section through an extruded metal product which may be usedfor producing a post as illustrated in FIG. 7.

Referring first to the embodiment which is illustrated in FIGS. 1 to 6inclusive, the expanded metal product formed by the invention is thepost 10 illustrated in FIG. 1. Such a postis useful for thesupporting-,ofoverhead power lines and the like. The post 10 comprisesacentral portion -11 which can be seen in section in FIGS. 2 and 4and'which is a tubular member, four trusses 12 which radiate outwardlyfrom the central portion 11, the central portion 11 forming one chord ofeach respective truss, and an outer flange 14 forming the other chordthereof, and a series of struts designated 15 interconnecting the chordsof the trusses and being inclined thereto, the trusses comprising asingle integral member of ductile metal, and the metal contained withinthe struts 15 being in a condition of having been strained beyond itsyield point by stretching of metal to form the struts 15.

The first stage in the production of the product of FIG. 1 is extrusionof a metal product designated 17 and illustrated in section in FIG. 2.The metal of the product 17 is essentially a ductile metal since itneeds to pass through a subsequent stretching operation for theformation of the struts l5, and a large number of aluminium alloys arefound to be suitable for use within this invention. The invention canhowever be used with other extrusile metals which also have ductileproperties. The required degree of ductility of course is determinedbythe required degree of stretch of the strut forming portions, which,after stretching, form the struts 15. The metal product 17, in beingextruded, is of constant cross-sectional shape, and has the centralportion 11 of tubular shape as described above, and a series of fourwebs l9 radiate outwardly from the central portion 11 to terminate attheir outer ends in the outer flanges 14. Each web 19 has in it a pairof ribs 20, the ribs 20 being between a respective flange 14 and thecentral portion 11.

FIG. 3 illustrates a further step in the formation of the expanded metalproduct, wherein metal is removed from each of the webs 19 to form threerows of slots designated 22, the length of each slot exceeding twice thelength of the metal designated 23 which remains between the ends of theslots and the adjacent end of the next slot in the same row, and asshown in FIG. 3 the slots of any one row on one side of a ribv 20 arestaggered relative to the slots of the row on the other side of that ribso as to form the rib into a plurality of strutforming portions whichare designated 24. (The lengths of the portions 24 are normally muchgreater than shown in FIG. 3, wherein the slots 22 are shown to be shortin length so that the principles of the invention may be more clearlyillustrated.) It may be noted that in this embodiment the width of theslots 22 is the same as the space between the ribs, or between a rib andthe central portion or between a rib and the flange as the case may be,since this enables a simple punching operation to take place wherein thecentral portion, the ribs and the flanges themselves form the back-updie for a punch, and a male punch only is required. In the alternative,if the slots are formed by a roll punching operation, the back-up rollerdoes not need to have slots therein to function as the female die. Thissimple expedient is another advantage of this invention.

FIG. 4 illustrates diagrammatically a section through stretching jaws,which are carried on the ends of pivoted clamping bars 28, and as shownin FIG. 6, the clamping bars 28 are arranged to be clamped by respectivepressure clamping cylinders 29'. As shown in FIG. 6, the stretching jaws27 on the left-hand side of the drawing are fixed, but those on theright-hand side are coupled to stretching cylinders 31 which areindependently operated to provide either a parallel or a tapered post10. In this embodiment the tapered post 10 is shown being produced bygreater movement of the lower stretching cylinder 31 than the upperstretching cylinder 31. Upon operation of the stretching cylinders 31,two opposite flanges 14 are forced away simultaneously from the centralportion 11, and this performs a double function on the strut-formingportions 24 of the extruded and slotted member which is illustrated inFIG. 3. The strut-forming portions are inclined relative to the outerflanges l4 and the central portion 11, and simultaneously they areelongated by a process of stretching, and this action forms the struts15 from the strut-forming portions 24, in turn forming the trusses 12which haveas their chords the central portion 11 and the outer flanges14.

The post 10 which is formed by this method and in accordance with thisinvention is pleasing in appearance, and contains an inbuilt conduit forprotection of electrical cables, the central portion 11 of coursefunctioning in this manner. The post is considerably stronger than otherposts of the same material and similar cost, andif the number of trussesis less than five then the punching and stretching operation is easily.effected. The ideal number of trusses isxfour as illustrated, sincethis enables two trusses to be formed simultaneously in one stretchingoperation, and also enables two webs to be punched in onepunchingoperation. Punching of course is rendered more difficultif the number oftrusses is increased.

FIGS. 7 and 8 illustrate respectively a'post and a section through theextrudedmetal product from which it is made in accordance with a secondembodiment. The post 35 illustrated in FIG. 7 is provided with twotubular portions 36 which form part of the central portion 11 of thepost, the tubular portions 36 being bent over to form two goose-necklamp supports at the upper end of the post ;as-illustrated in-FIG. 7.The webs 37 each contain only one rib 38: between the central portion 11and the outer flanges 14. Each web 37 is punched with a row of slots oneach side of its rib 38, the slots overlapping as described aforesaid,and each truss designated 39 in FIG. 7 has only one series of struts 40,as compared with two series of struts in the first'embodiment. Such apost is lower in cost but slightly less rigid than the post illustratedin the first embodiment. Y

If'the invention. is utilised with an extrusion of suitablecross-sectional -shape, it will be seen that the flanges may themselvesbe tubular in section, this arrangement having the advantage of morerigidity than the posts which are illustrated in the above embodiments.I

With the appropriate cross-sectional shape of extruded product, anexpanded metal product can be formed which is useful as a beam, and forexample may be used in situations where strength is required in morethan one plane.

What I claim is:

1. The method of producing an expanded metal product comprising:

a. extruding ductile metal to form an extruded product having a constantcross-sectional shape which includes a centralportion with at leastthree circumferentially spaced webs radiating outwardly therefrom, eachweb terminating at its outer end in an outer portion, and each webhaving a rib extending along it, each rib being between the outerportion and the central portion,

removing metal from each web so as to form a row of slots on each sideof the rib thereof, the length of each slot exceeding twice the lengthof metal remaining between either one of its ends and the adjacent endof the next slot in the same row, and the slots on a row on one side ofthe rib being staggered relative to those of the row on the other sideso as to form the rib into a plurality of strut-forming portions, and

c. forcing respective said outer portions away from the' central portionto thereby incline the strutforming portions of the ribs relative bothto the respective outer portions and to the central portion and at thesame time elongate the metal thereof by stretching it, thus formingstruts joining respective outer portions and the central portion so asto in .turn form trusses, the chords of which are constituted bysaidcentral portion and respective said outer portions.

2..A method of producing an expanded metal product according to claim 1comprising forming each said web to contain only one rib, and formingtwo rows of said slots with one row on each side of said rib.

3. A method of producing an expanded metal prod uct according to claim 1further comprising clamping said outer portions in stretching jaws of astretching machine, and moving said stretching jaws apart to therebyeffect elongation and inclination of said strutforming portions.

.4. A method of producing an expanded metal product according to claim 1further comprising clamping said'outer portions in stretching jaws of astretching machine, and moving the jaws of said stretching machine apartby different amounts along their lengths to web to contain a pluralityof ribs, forming a row of said slots between the ribs of each adjacentpair of ribs, forming a further row of slots on the outer side of theoutermost rib in each web, and forming a still further row of slots onthe inner side of the innermost rib of each web.

1. The method of producing an expanded metal product comprising: a.extruding ductile metal to form an extruded product having a constantcross-sectional shape which includes a central portion with at leastthree circumferentially spaced webs radiating outwardly therefrom, eachweb terminating at its outer end in an outer portion, and each webhaving a rib extending along it, each rib being between the outerportion and the central portion, b. removing metal from each web so asto form a row of slots on each side of the rib thereof, the length ofeach slot exceeding twice the length of metal remaining between eitherone of its ends and the adjacent end of the next slot in the same row,and the slots on a row on one side of the rib being staggered relativeto those of the row on the other side so as to form the rib into aplurality of strut-forming portions, and c. forcing respective saidouter portions away from the central portion to thereby incline thestrut-forming portions of the ribs relative both to the respective outerportions and to the central portion and at the same time elongate themetal thereof by stretching it, thus forming struts joining respectiveouter portions and the central portion so as to in turn form trusses,the chords of which are constituted by said central portion andrespective said outer portions.
 2. A method of producing an expandedmetal product according to claim 1 comprising forming each said web tocontain only one rib, and forming two rows of said slots with one row oneach side of said rib.
 3. A method of producing an expanded metalproduct according to claim 1 further comprising clamping said outerportions in stretching jaws of a stretching machine, and moving saidstretching jaws apart to thereby effect elongation and inclination ofsaid strut-forming portions.
 4. A method of producing an expanded metalproduct according to claim 1 further comprising clamping said outerportions in stretching jaws of a stretching machine, and moving the jawsof said stretching machine apart by different amounts along theirlengths to thereby form a product wherein said outer portions areinclined to one another.
 5. The method of producing an expanded metalproduct according to claim 1 further comprising extruding said centralportion to be of hollow section throughout its length.
 6. A method ofproducing an expanded metal product according to claim 1 comprisingforming each said web to contain a plurality of ribs, forming a row ofsaid slots between the ribs of each adjacent pair of ribs, forming afurther row of slots on the outer side of the outermost rib in each web,and forming a still further row of slots on the inner side of theinnermost rib of each web.